Synchronized Switch Harvesting Research Articles

High‐Efficiency Energy Management Circuit Combining Synchronized Switch Harvesting on Inductor Rectifier and Impedance Matching for Impact‐Type Piezoelectric Energy Harvester

To improve the output power of impact‐type piezoelectric energy harvesters (IPEHs), a high‐efficiency energy management circuit combining a self‐powered synchronized switch harvesting on inductor (SP‐SSHI) rectifier and an alternative impedance matching circuit is proposed. The SP‐SSHI rectifier eliminates the effect of inherent capacitance of IPEH through LC oscillation and enhances the output power. The alternative impedance matching circuit provides two optimal load resistances for different periods of IPEHs to increase the harvested power. Furthermore, to decrease the power dissipation, the proposed circuit is activated only when the output power of IPEH is sufficiently high and the SSHI is active. A control chip of the proposed circuit is designed and fabricated in a 0.18 μm complementary metal‐oxide semiconductor process. The proposed circuit is applied for a microwind IPEH, and the peak figure of merit and efficiency are 3.68 and 90.4%, at the wind speed of 1.46 m s−1, respectively. The results indicate a significant improvement in output power and harvesting efficiency of the proposed IPEH‐specialized circuit. When a flame sensor (USEQFSEA22L80) is powered by the microwind energy harvesting system, the proposed circuit increases operating time of the sensor as 4.6 times, as compared with the traditional impedance matching circuit.

Analysis and optimization of self-powered parallel synchronized switch harvesting on inductor circuit for piezoelectric energy harvesting

Due to its strong environmental robustness and high energy density, piezoelectric energy harvesting is considered one of the most promising methods to power wireless sensor nodes under extreme conditions. The interface circuit is essential to a piezoelectric energy harvester to reduce internal energy dissipation, achieve impedance matching, and improve energy conversion efficiency. Existing researches show that a parallel synchronized switch harvesting on inductor (P-SSHI) interface circuit compared with a standard energy harvesting (SEH) circuit can significantly improve the output power. Therefore, this paper proposes a self-powered optimized PSSHI (SP-OPSSHI) circuit, which adopts a new peak detection switching circuit to replace the switches in the P-SSHI circuit. It can realize switch control without an external starting power supply, i.e. cold start. Compared with an existing self-powered PSSHI (SP-PSSHI) circuit, it can effectively eliminate the ‘second inversion’ phenomenon caused by the parasitic capacitors of transistors after the voltage inversion process. The cause and effect of ‘second inversion’ on energy harvesting are analyzed in this study. Then, the working principle and process of the optimized circuit are discussed, and energy harvesting under the ideal state is conducted. Finally, the SP-OPSSHI circuit is developed and tested. The experimental waveforms show that the SP-OPSSHI circuit compared with the SP-PSSHI circuit can significantly reduce the impact of parasitic capacitors in the energy harvesting process. The output performance of the SP-OPSSH circuit is tested with the variation of resistance. The experimental results indicate that the SP-OPSSHI circuit has an optimal load resistance of 350 kΩ, achieving a maximum harvested power being 2.91 times that of the SEH circuit.

High Gain, Load-Tolerant Self-Powered Series–Parallel Synchronized Switching Technique for Piezoelectric Energy Harvesting

In the framework of autonomous wireless devices ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e.g.</i> , sensors) powered by energy available from their surrounding environment, this article exposes a technique combining the so-called series and parallel Synchronized Switch Harvesting on Inductor (SSHI) approaches for piezoelectric energy harvesting. More specifically, the proposed circuit consists in switching the piezoelectric element on two inductors, one in series between the piezoelement and the energy extraction stage (rectifier bridge) and the other one in parallel with the rectifier. This, therefore, allows several energy transfer processes to occur per half period, even when the switching process is finished. Based on numerical analysis supported by experimental validations, it is shown that such a technique permits a significant widening of the effective load and rectified voltage ranges, but also, under particular conditions, a power output magnification that is even larger than in the sole SSHI case.

An inductorless P-SSHC piezoelectric energy harvesting integrated system with high flipping efficiency

This paper presents an inductorless piezoelectric energy harvesting integrated system with high flipping efficiency using P-SSHC. Since the rectifier using parallel synchronized switch harvesting on capacitor (P-SSHC) has a trade-off between the rectification efficiency and the system volume, a voltage flipping optimization method for the parasitic capacitor of the piezoelectric source is proposed in this paper. It sets the proportional relationship between the flipping and parasitic capacitor, achieving optimal voltage flipping efficiency and improving rectification efficiency. In addition, to achieve the miniaturization of the system, this paper uses a switched capacitor (SC) DC/DC converter with a variable voltage conversion ratio (VCR) to replace the traditional inductive type DC/DC converter. The proposed system was implemented in a 0.18 μm BCD process with a core circuit chip area of 1152 × 585 μm2. The voltage flipping efficiency of the designed rectifier reaches 74%. The overall system does not use inductors. Within the open-circuit voltage range of 1–1.8 V, it achieves a peak end-to-end conversion efficiency of 81.45% and a peak voltage tracking efficiency of 98.89%.

Self-Powered Dual-Inductor MI-PSSHI-VDR Interface Circuit for Multi-PZTs Energy Harvesting

Vibration energy harvesting using multiple piezoelectric transducers (multi-PZTs) can increase its output power and environmental adaptability. At present, there are still few research articles on multi-input interface circuits for multi-PZTs, especially those using the parallel synchronized switching harvesting on inductor (PSSHI) technique. Therefore, this article presents a self-powered dual-inductor MI-PSSHI voltage doubler rectifier (VDR) interface circuit. It can process multi-PZT voltages with arbitrary phases input. The measurements demonstrate that the prototyped MI-PSSHI-VDR circuit can extract a peak power of 1.93 mW from four PZTs under an excitation of 1.5 g and 77.5 Hz. The energy integration efficiency and energy extraction efficiency of the prototyped circuit are 93.2% and 75.1%. Compared with a multi-input full-bridge rectifier, the proposed circuit can achieve 3.22× power improvement and 3.58× voltage improvement, which grasps a good balance between the indices of peak output power and load voltage range. Additionally, the MI-PSSHI-VDR circuit is easy to implement and shows a good scalability, which can be an alternative solution for multi-PZTs energy harvesting.

Investigation of a nonlinear piezoelectric energy harvester with advanced electric circuits with the finite element method

In this contribution, a system simulation method based on the finite element method (FEM) is applied to simulate a strongly coupled bimorph piezoelectric vibration-based energy harvester (PVEH) with various nonlinear, non-ideal and active circuits: The standard circuit, the synchronized switch harvesting on inductor circuit and the synchronized electric charge extraction circuit are considered. Furthermore, nonlinear elastic behavior of the piezoelectric material is taken into account and harmonic base excitations of different magnitudes at a fixed frequency are applied. The holistic FEM-based system simulation approach solves the complete set of piezoelectric equations together with the equation of the electric circuit such that all electromechanical coupling phenomena are taken into account. This fully coupled numerical analysis enables the detailed evaluation of the influences of the electric circuits on the vibrational behavior and the harvested energy of the PVEH with respect to the magnitude of base excitation. Results from literature on the efficiency of electric circuits are confirmed and interactions between mechanical and electrical nonlinearities of PVEHs are revealed.Article highlightsSystem simulations of a mechanically and electrically nonlinear piezoelectric energy harvester are performed using only one software tool.The infuence of electric circuits on the vibration behavior and the effciency of an energy harvester are investigated in detail.Interactions between mechanical and electrical nonlinearities of an energy harvester are revealed.

Analytical Study of Piezoelectric Harvesters With SECE and SSHI Under Variable Excitation

A theoretical analysis aimed at predicting the power extracted from resonant piezoelectric vibration energy harvesters feeding synchronous switching-type electronic interfaces under variable mechanical excitation is proposed. In particular, for the widely used synchronous electric charge extraction (SECE) and synchronized switching harvesting on an inductor (SSHI) switching interfaces, the nonlinear equations describing the circuit behavior are solved under reasonable assumptions, and closed-form expressions of the extracted power are derived as a function of the circuit parameters and of the vibration characteristics, in the case of modulated mechanical vibrations. Numerical and experimental results validate the proposed closed-form expressions and show their usefulness for design purposes.

Topology network effects for DSSH circuit on vibration energy harvesting using piezoelectric materials

&lt;span lang="EN-US"&gt;Energy extraction takes place using several different technologies, depending on the type of energy and how it is used. The objective of this paper is to study topology influence for a smart network based on piezoelectric materials using the DSSH (Double Synchronized Switch Harvesting). In this work, has been presented network topology for circuit DSSH (DSSH Standard, Independent DSSH, DSSH in parallel, Mono DSSH, DSSH in series). Using simulation-based on a structure with embedded piezoelectric system harvesters, then compare different topology of circuit DSSH for knowledge is how to connect the circuit DSSH together and how to implement accurately this circuit strategy for maximizing the total output power. The network topology DSSH extracted power a technique allows again up to in terms of maximal power output compared with network topology standard extracted at the resonant frequency. The simulation results shows that by using the same input parameters the maximum efficiency for topology DSSH in parallel produces 120% more energy than topology DSSH-series. In addition, the energy harvesting by Mono-DSSH is more than DSSH-series by 650% and it has exceeded DSSH-ind by 240%.&lt;/span&gt;&lt;span lang="EN-US"&gt;Energy extraction takes place using several different technologies, depending on the type of energy and how it is used. The objective of this paper is to study topology influence for a smart network based on piezoelectric materials using the DSSH (Double Synchronized Switch Harvesting). In this work, has been presented network topology for circuit DSSH (DSSH Standard, Independent DSSH, DSSH in parallel, Mono DSSH, DSSH in series). Using simulation-based on a structure with embedded piezoelectric system harvesters, then compare different topology of circuit DSSH for knowledge is how to connect the circuit DSSH together and how to implement accurately this circuit strategy for maximizing the total output power. The network topology DSSH extracted power a technique allows again up to in terms of maximal power output compared with network topology standard extracted at the resonant frequency. The simulation results shows that by using the same input parameters the maximum efficiency for topology DSSH in parallel produces 120% more energy than topology DSSH-series. In addition, the energy harvesting by Mono-DSSH is more than DSSH-series by 650% and it has exceeded DSSH-ind by 240%.&lt;/span&gt;

ReL-SSHI rectifier based piezoelectric energy harvesting circuit with MPPT control technique

Rectifier-Less Synchronized Switch Harvesting on Inductor (ReL-SSHI) interface is one of the most efficient interfaces for weakly-coupled piezoelectric (PE) systems. However, ReL-SSHI interface has narrow optimal rectified voltage range. Therefore, in this paper a maximum power point tracking (MPPT) circuit is presented for ReL-SSHI interface. An envelope extractor and a hysteresis voltage controller are used in the MPPT, which can monitor the open circuit (OC) voltage of piezoelectric transducer (PZT) during Energy Harvesting (EH). Simulation shows the maximum MPPT efficiency can reach up to 99.1% and the Figure of Merit (FoM) factor can achieve 6.4. The measurements confirm the simplicity and efficiency of the proposed MPPT solution for the weakly-coupled piezoelectric energy harvesting (PEH).

A Low-Power High-Efficiency Adaptive Energy Harvesting Circuit for Broadband Piezoelectric Vibration Energy Harvester

Existing piezoelectric vibration energy harvesting circuits require auxiliary power for the switch control module and are difficult to adapt to broadband piezoelectric vibration energy harvesters. This paper proposes a self-powered and low-power enhanced double synchronized switch harvesting (EDSSH) circuit. The proposed circuit consists of a low-power follow-up switch control circuit, reverse feedback blocking-up circuit, synchronous electric charge extraction circuit and buck-boost circuit. The EDSSH circuit can automatically adapt to the sinusoidal voltage signal with the frequency of 1 to 312.5 Hz that is output by the piezoelectric vibration energy harvester. The switch control circuit of the EDSSH circuit works intermittently for a very short time near the power extreme point and consumes a low amount of electric energy. The reverse feedback blocking-up circuit of the EDSSH circuit can keep the transmission efficiency at the optimal value. By using a charging capacitor of 1 mF, the charging efficiency of the proposed EDSSH circuit is 1.51 times that of the DSSH circuit.

Investigations on energy harvesting systems incorporating mechanical and electrical nonlinearities to charge reusable batteries

This report analyzes the electromechanical coupling evident in vibration energy harvesting systems that charge reusable batteries. A model of a vibration energy harvesting system with far-from-equilibrium nonlinearities is considered for sake of capitalizing on high-energy forced vibrations. The piezoelectric structure is coupled with nonlinear interface circuits that leverage rectification and control stages to enhance power delivery to the battery. Three circuits, namely standard energy harvesting (SEH) circuit, parallel synchronized switching harvesting on inductor (P-SSHI) circuit, and synchronized charge extraction (SCE) are considered as interfaces between the nonlinear energy harvester and a battery. A simplified power calculation is numerically verified to accurately estimate the harvested power respectively delivered from three interface circuits to the battery. The investigations reveal that increasing required battery voltage may inhibit means to achieve high-energy vibrations and thus prevent battery charging. By a conservation of energy, it is shown that the phase lag between beam velocity and the base acceleration is the primary indicator of interference between dynamic energy flows in the electromechanical sub-systems. This research sheds light on the influences of energy storage components on the functioning of nonlinear vibration energy harvesting systems. Moreover, the principles uncovered for the inhibition of high-energy oscillation may guide future nonlinear energy harvesting system design to extract the best power out from the ambient vibration environments.

A Novel MPPT Technique Based on the Envelope Extraction Implemented With Passive Components for Piezoelectric Energy Harvesting

This article presents a rectifierless synchronized switch harvesting on inductor interface with a novel maximum power point tracking (MPPT) technique assistance for piezoelectric energy harvester (PEH). The proposed MPPT solution captures vibration states through an envelope extractor and then adjusts the rectified voltage to achieve the maximum power harvest. The MPPT method tracks the vibration amplitude through an envelope extractor, which no longer disconnects the PEH from the converter to measure its open-circuit voltage. Hence, energy harvesting and maximum power point finding can be achieved simultaneously. Besides, the MPPT solution was implemented through discrete passive analog components with ultralow power consumption, which can achieve the MPPT operation when the harvester was cold started. The experiment confirms the simplicity and efficiency of the proposed MPPT solution for the PEH, and the maximum MPPT efficiency can reach 99.5%.

Nonlinear finite element system simulation of piezoelectric vibration-based energy harvesters

Piezoelectric vibration-based energy harvesters consist of an electromechanical structure and an electric circuitry, influencing each other. We propose a novel approach that allows a finite element based system simulation of nonlinear electromechanical structures coupled to nonlinear electric circuitries. In the finite element simulation the influence of the electric circuit on the electromechanical structure is considered via the vector of external forces, using an implicit time integration scheme. To demonstrate the applicability of the new simulation method an active power circuit is considered. Several examples of piezoelectric vibration-based energy harvesters, connected to standard or synchronized switch harvesting on inductor (SSHI) circuits, showing linear or nonlinear mechanical behavior, are studied to validate the proposed simulation method against numerical results reported in the literature. The advocated method allows for consistent and efficient simulations of complete nonlinear energy harvesters using only one software tool.

Synchronized switch piezoelectric energy harvesting using rotating magnetic ball and reed switches

Synchronized switch harvesting on inductor (SSHI) interface circuit has been developed to boost the harvesting capability of piezoelectric energy harvesters (PEHs). Although some electronic self-powered peak-detector and switching circuits have been proposed to support the practical realization of SSHI, the energy dissipation and voltage drops in transistors and diodes of the self-powered circuits might significantly deteriorate the actual energy harvesting performance. Some mechatronic designs were proposed as well. However, most of their switches are activated by touch impacts, which might introduce undesired high-order vibrations to the main structure. In this paper, rather than using the impact-engaged strategy discussed in the literature, a new mechanism using a magnetic ball for vibration synchronization and reed switches for switching operation is proposed. A PEH shunted to an SSHI interface circuit using the proposed mechatronic approach has been prototyped. Since the peak-detection and switching operations are completed by a mechanical mechanism, less passive electrical components, which consume extra energy, are required in our proposed design. Therefore, the overall energy harvesting performance is improved. Numerical simulations and experimental tests have validated the feasibility of the proposed design. The experimental results have shown that the power output produced by the proposed mechatronic self-powered SSHI design can be increased by and , as compared with the cases using a benchmark standard energy harvesting bridge rectifier and an electronic self-powered SSHI solutions, respectively. Moreover, owing to the new mechatronic design, the auxiliary mechanical components are embedded in the tip block of the cantilevered PEH, rendering the whole system to be a compact design.

Lumped Parameter Evaluation Model Analysis and Load Coupling Modeling of Piezoelectric Composite Cantilever Beam

In order to study the working mechanism of piezoelectric composite cantilever beam and improve the ability of predicting the power generation performance of piezoelectric composite cantilever vibration energy harvester (CVEH), the simple and high-precision analysis models of equivalent mass and equivalent stiffness of CVEH are proposed. The natural frequency method is used to compare the calculation results of the evaluation model, Rayleigh Ritz method and finite element simulation, and the results show that the consistency (Ω) between the evaluation model and the finite element simulation is more than 95%. The influence of the mass ratio (α) between the end mass of the beam and the weight of the beam itself on Ω is analyzed by using the proposed evaluation model, which shows that Ω increases with the increase of α, and the increase is more significant in the range of 0<α<4. The analysis of the influence of α on the natural frequency of the beam () shows that decreases with the increase of α, and the decrease is more obvious in the range of 0<α<2. According to the evaluation model, the electromechanical conversion analysis models of CVEH and its control equation with coupling of standard energy harvesting (SEH) interface circuit and Double synchronous switch harvesting (DSSH) interface circuit are established respectively, and the mathematical models of its output voltage are derived. The power generation experiment of CVEH is carried out, and the results show that the proposed models are in good agreement with the experimental results.

Enhancement of surge-induced synchronized switch harvesting on inductor strategy

We propose and demonstrate a novel method to enhance vibration harvesting based on surge-induced synchronized switch harvesting on inductor (S3HI). S3HI allows harvesting of a large amount of energy even from low-amplitude vibrations by inducing a surge voltage during the voltage inversion of a synchronized switch harvesting on inductor (SSHI). The surge voltage and the voltage amplification from the conventional voltage inversion improve energy harvesting. S3HI modifies SSHI by both rewiring the circuit without adding components and using a novel switching pattern for voltage inversion, thus maintaining the simplicity of SSHI. We propose a novel switching strategy and circuit topology and analyze six methods that constitute the S3HI family, which includes traditional S3HI and high-frequency S3HI. We demonstrate that the six methods suitably harvest energy even from low-amplitude vibrations. Nevertheless, the harvestable energy per vibration cycle depends on the switching pattern and storage-capacitor voltage. The use of the proposed switching strategy, which allows energy harvesting before energy-dissipative voltage inversion, substantially increases the harvestable energy per vibration cycle. In the typical case considered in this study, the said increase is on the order of 11%–31% and 15%–450% compared to the traditional and existing high-frequency S3HI methods, respectively, depending on the storage-capacitor voltage. Additionally, the proposed circuit can be used as a traditional circuit. It could be considered a promising alternative to S3HI methods owing to its potential auto-reboot capability, which is not found in traditional S3HI circuit.

Enhancing output power of rotational electret energy harvester by synchronized switch harvesting on inductor

A nonlinear interface circuit, known as synchronized switch harvesting on inductor (SSHI), for in-plane rotational electret kinetic energy harvesters (EHs) was developed. An explicit generator model is derived to verify the applicability of SSHI, which was originally proposed for the piezoelectric EH, on an in-plane electret EH. Experimentally, 505 μW was harvested with SSHI at a rectified voltage of 142 V for an in-plane rotational electret EH rotating at 1 rps, which is 2.47 times of that with a full-bridge rectifier, and which is in good agreement with the simulation result. The circuit efficiency and criteria for the inductor selection were clarified through circuit analysis based on spice simulation. It is found that the power dissipation of voltage-divider and rectification diodes becomes pronounced as the load voltage increases, constraining the efficiency. The inductor, which usually dominates the circuit volume, can be miniaturized for electret EHs, because the voltage inversion ratio, a benchmark of the SSHI performance, turns out to be insensitive to the series resistance of the inductor. The self-powering ability of the proposed circuit is also presented.

A novel control circuit for piezoelectric energy harvesting

A novel piezoelectric energy harvesting circuit is proposed. This circuit consists of a piezoelectric element, synchronized switch harvesting on capacitors (SSHC) circuit, two sampling resistors, control circuit, full-bridge rectifier, and load. The control circuit is composed of a zero-crossing detection circuit and a pulse generation circuit. The zero-crossing detection circuit adopts sampling resistance method, which is more accurate and easier to implement than the traditional voltage comparison method. The control signal for controlling switches in the SSHC circuit is generated by pulse generation circuit and its width is dynamically adjusted according to the state of the flipping process. Compared with circuit that uses capacitors to control the width of the control signal, this circuit is easier to implement and has a higher output efficiency. Experiment results show that the circuit proposed can accurately detect the zero-crossing time and automatically adjust the pulse width of the control signal according to the state of the circuit. The output power of the proposed circuit is 1.80 ​mW with 10 ​kΩ load resistance, which is four times that of the traditional SSHC circuit.

Ltspice Simulation of Non Linear Technique SSHI Serial and SSHI Parallel of Piezoelectric Vibration Energy Harvesting

in this paper, a simple but effective proposal for piezoelectric energy collectors. synchronized switching harvesting in the SSIH technique (synchronized switch harvesting on parallel inductor consists in placing a switch which will be commanded on closing at the instant when the amplitude of the vibrations passes through the extreme this technique makes it possible to increase the power harvested from a ratio of 8 compared to the power of a harvester based on ac dc converter similarly the SSIH command (synchronized switch harvesting on inductor for LT SPICEs-based simulations of the two techniques is carried out finally a comparison with respect to the standard structure of energy harvesting is made in order to validate theoretical concepts

A Low-Profile Autonomous Interface Circuit for Piezoelectric Micro-Power Generators

This paper presents a low-profile and autonomous piezoelectric energy harvesting system consisting of an extraction rectifier and a maximum power point tracking (MPPT) circuit for powering portable electronics. Synchronized switch harvesting on capacitor-inductor (SSHCI) technique with its unique two-step voltage flipping process is utilized to downsize the ponderous external inductor and extend application areas of such harvesting systems. SSHCI implementation with small flipping inductor-capacitor combination enhances voltage flipping efficiency and accordingly attains power extraction improvements over conventional synchronized switch harvesting on inductor (SSHI) circuits utilizing bulky external components. A novel MPPT system provides robustness of operation against changing load and excitation conditions. Innovation in MPPT comes from the refresh unit, which continually monitors excitation conditions of piezoelectric harvester to detect any change in optimum storage voltage. Compared with conventional circuits, optimal flipping detection inspired from active diode structures eliminates the need for external adjustment, delivering autonomy to SSHCI. Inductor sharing between SSHCI and MPPT reduces the number of external components. The circuit is fabricated in 180 nm CMOS technology with 1.23 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> active area, and is tested with custom MEMS piezoelectric harvester at its resonance frequency of 415 Hz. It is capable of extracting 5.44x more power compared to ideal FBR, while using $100~\mu $ H inductor. Due to reduction of losses through low power design techniques, measured power conversion efficiency of 83% is achieved at 3.2 V piezoelectric open circuit voltage amplitude. Boosting of power generation capacity in a low profile is a significant contribution of the design.